Isaiah 56 - 66 has the theme of "How to Prepare for the Coming Glory." In fact Isaiah 56 points out who will receive this glory -- the coming Messiah. He states that the eunuch and the foreigner will both be included with God's chosen. This is a major new truth for the Israelites.
To them a eunuch had no hope because they were physically blemished and the foreigner was gentile/heathen. However Isaiah says that the Lord will save not only the eunuch but also the foreigner.
Israel looked down on both groups of people, but God states "The Lord God, who gathers the outcasts of Israel, declares, I will gather yet others to him beside those already gathered." (verse 8)
This is the first truth of this section of Scripture. The second truth is also found in Isaiah 56:9-12. Here the prophet condemns the shepherds (leaders) of Israel. He describes them as lazy/silent dogs who love to dream, slumber, and take from God's people.
The future of Israel is discussed. Then in Chapter 61 we see what the Messiah will do when he comes. It is this passage that Jesus quoted from in Luke 4 and declared he was the Messiah. The EVS Study Bible states that the Messiah will preach into existence his new, liberated people, who will pray into existence his new, redeemed world. Is this not what Jesus did?